1. Field of the Invention
The present invention relates to a grasping forceps for use in conjunction with endoscopic instruments, for example a ureteroscope, wherein the forceps, with an appropriate grasping distal end, extends through and is manipulated beyond the positioned instrument for capturing the target, for example, a stone, stent, clump of tissue, or the like.
Such forceps, as well as the above referred to relationship thereof to endoscopic instruments, are well known in the art and are principally intended for manual control by a single hand wherein both the thumb and fingers are used for manipulation of the functioning components.
A common form of grasping forceps utilizes three or four flexible grasping prongs or claws outwardly diverging from the end of a flexible shaft or cable and selectively retracted into grasping engagement upon telescopic retraction within a cable surrounding sleeve which inwardly biases the claws into generally coaxial alignment with the cable. However, inasmuch as the distal ends of the collapsed claws frequently remain exposed, both the claws and the interior of the scope tend to become damaged during passage of the forceps through the scope's working channel. Any such damage or disruption during a surgical procedure is clearly undesirable.
Avoidance of this problem of potential damage to both the scope and the forceps by an extension of the collapsing sleeve beyond the ends of the claws also raises significant problems. More specifically, in light of the normally sharpened and in-turned nature of the tips of the forcep claws, any complete collapsing and interengagement of these tips will result in a tendency of the tips to interlock or jam together whereby automatic opening of the claws either will not occur at all upon retraction of the collapsing sleeve, or will do so in an uneven and unpredictable manner, neither situation of which would be acceptable.
Another problem commonly encountered with known grasping forceps is the difficulty in maintaining the gripping or grasping claws, during collapsing engagement with the object, at a fixed axial location relative to the end of the scope and the target object itself. In other words, many forceps effect the closing of the claws by an axial retraction of the claws into a collapsing sleeve which results in a tendency to simultaneously retract from the target object.